1. The Field of the Invention
The present invention relates generally to the field of microscopy. More specifically, the invention relates to using a fluorescence microscope and nanoparticles to perform transmission microscopy of diffuse materials.
2. The Relevant Technology
Microscopy is the technical field of using microscopes to view samples or objects. Optical microscopes were first developed in the 17th century. Since then, microscopy has grown to the point where there are several types of microscopes and scores of different methods available for viewing samples. The development of microscopy revolutionized biology and remains an essential tool in that science, along with many others including materials science and numerous engineering disciplines.
A well know and widely used technique for performing optical microscopy is transmission microscopy, which involves passing visible light through a sample. The transmitted light is then passed through one or more lenses to provide a magnified view of the sample. The transmitted light can be detected directly by the eye, imaged on a photographic plate, or captured digitally. A single lens with its attachments, or a system of lenses and imaging equipment, along with the appropriate lighting equipment, sample stage and support, makes up the basic light microscope.
Transmission microscopy has many advantages. For instance, the necessary equipment is relatively simple to set up and use. Furthermore, samples being observed often do not require extensive preparation. This allows some live cells to be viewed. There are, however, various limitations associated with transmission microscopy. Transmission microscopy can usually only effectively image dark or strongly refracting objects, or objects with sufficient contrast. Many biological samples, including many live cells, generally lack sufficient contrast to be studied successfully because the internal structures of the cells are colorless and transparent. The most common way to increase contrast in a sample is to stain the different structures with selective dyes. Staining the sample involves killing and fixing the sample. Additionally, staining may also introduce artifacts that appear as structural details of the sample, but which are caused by the processing of the sample and are thus not legitimate features of the sample. Additionally, without using far more complex techniques, the diffraction limit of light limits the spatial resolution of the sample image to approximately half of the wavelength of light. Still further, the resolution/clarity of the image can be limited or negatively affected by out of focus light from points outside the focal plane.
Another widely used method is known as laser or fluorescence microscopy, in which a laser is used to make a specimen emit light, either because the specimen does so naturally or because it has been injected with fluorescent dye. More specifically, when certain compounds are illuminated with high energy light, they then emit light of a different frequency. This absorption-emission effect is known as fluorescence. Just as staining a sample with a dye for transmission microscopy kills the specimen, the injection of a fluorescent dye into a specimen viewed by fluorescence microscopy also leads to killing the specimen. More particularly, when excited by the laser light used during fluorescence microscopy, such dyes generate toxic chemicals that kill living cells.
Fluorescence microscopy is strictly limited to suitably autofluorescent or stained samples. Therefore, fluorescence microscopy is sensitive primarily to the surfaces of a specimen (such as cell membranes) from which light emission occurs. However, many material properties in the life sciences and in materials science are controlled by the bulk arrangement of matter. Thus, such materials are best probed by transmission microscopy. As discussed above, however, typical transmission microscopy is subject to limitations that prevent the obtaining of clear, high resolution images of many samples.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.